The present invention relates generally to an equalizer, and more particularly, to an improved dielectric resonator equalizer that does not employ circulators.
The assignee of the present invention manufactures and deploys satellites that orbit the earth and which carry communication equipment. Equalizers are employed as part of the communication equipment. Conventional equalizers include a reflective equalizer using circulator or a self equalized filter. However, circulators are problematic in that they exhibit temperature stability and isolation problems.
It would therefore be advantageous to have a dielectric resonator equalizer that does not employ circulators.
To meet the above and other objectives, the present invention comprises a dielectric resonator equalizer that couples a dual-mode dielectric resonator to a planar transmission line, creating an all-pass network. Coupling is achieved using circular polarization of the electromagnetic field in the dielectric resonator. The all-pass, non-reciprocal network is realized by the use of circular polarized energy and an offset cross shaped, through transmission line.
An exemplary dielectric resonator equalizer comprises a cavity having first and second orthogonal tuning screws extending through its wall into the interior thereof and first and second opposed mode decoupling screws 14, 15 extending through the wall into the interior thereof.
A dual-mode dielectric resonator is disposed in the cavity. Input and output connectors are disposed at opposite ends of the cavity and are coupled to a transmission line that is disposed in the cavity. The transmission line has an offset cross shape. An aperture coupling or iris is disposed in the cavity between the transmission line and the dual-mode dielectric resonator.
A second dual-mode dielectric resonator may also be disposed in the cavity that is separated from and coupled to the dual-mode dielectric resonator by way of a second aperture coupling or iris.